Managing Projects

I like creative, messy projects. But the problem is how to manage them for content. The easiest thing to do would be to assign the project for students to do on their own time...but this doesn't work. A few do it but many of them don't. I know the project should be a culmination of what the students have learned, so when I do projects I want lots of content. Some teachers might say that projects take too much time. But I think students can really learn by getting into something on their own. My first year teaching I would get so frustrated with projects. What I've discovered is the key is structure and chunking. Each year I get better at this but it is still a challenge. Every year I find myself changing, revising and trying to make projects more engaging and manageable on my end!